Refactoring: request--parse-data is a method on response
Fix request--callback

Sometimes BUFFER given as the argument is different from the
buffer already set in RESPONSE.  That's why it is needed to be
reset before calling request--parse-data.
Do not handle error in request--parse-data
Cut and save header before running parser
Fix regexp used in request--cut-header
Do not clean header in request--curl-preprocess
Do not try to parse header when error is thrown
Check error-thrown before calling request--parse-data
Log response buffer-string
Simplify request--cut-header
Fix tests request--curl-preprocess/*
Add request-response-header
Fix test request-tfw-server

all tests are green now
Better request-response-header
Fix request--cut-header
Merge branch 'request-response-header'

* request-response-header method is added.
* Parser callback cannot access to raw header now.
Store redirect headers
More tests on redirects (failing)
Fix request--curl-absolutify-location-history

This fixes redirects test for curl backend
Fix request--url-retrieve-callback